Tool.



I. W. LlTCHFIELD.

TOOL.

APPLICATION FILED OCT- 30, 1913.

Patented. Dec. 12, 1916.

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' of Massachusetts, have ISAAC W. IPITCHFIELD, F BOSTON, MASgACHUSETTS.

TOOL.

Specification of Letters Patent.

Patented Dec... 112, rare.

Application filed October so, 1913. Serial no. 798,916.

To all whom it may concern Be it known that I, IsAAo W. LITCHF'IELD, acitizen of the United States, residing at Boston, in the county ofSuffolk and State invented certain new and useful Improvements in Tools;and I do hereby declare the following to be a full, clear, and exactdescription ofthe invention such as will enable others skilled in theart to which it appertains to make and use the same.

This invention relates to a tool of the class comprising relativelymovable jaws for gripping or'operating upon an object ated between themand a lever or levers for relatively actuating the jaws.

The object of the invention is to produce a tool of the class referredto which may tance through ,of the tool in be operated with greaterfacility and efficiency than tools which have heretofore been devised,and to produce a toolin which the jaws are relatively actuated in animproved and novel manner.

With the above object in view, the invention consists in the devices andcombinations of devices hereinafter described and particularly definedin the claims.

In the drawings illustrating the invention in the best form at presentknown to the inventorz-Figure 1 is a side elevation of a tool embodyingthe invention with a portion thereof removed to more clearly show thestructure, illustrating the. jaws of the tool in closed position; Fig. 2is a side elevation similar to Fig. 1 showing the jaws open position andan object located between the jaws; Fig. 3 is a front elevation of thetool. 7

It is a well known principle of mechanics that in any system of leversor other mechanical elements, the ratio of the resultant force exertedto the force applied, neglecting friction, is equal to the ratio of thedis which the point of application of the force applied moves to thedistance through which the point of application of the resultant forcemoves against the resistance. Therefore the greater the ratio of thedistance through which the point of application of the applied forcemoves to the distance through which the point of application of theresultant force moves, the greater the mechanical advantage secured bythe system.

In tools of this class heretofore devised, the entire closing movementof the jaws is tive produced by a singlerelative closing or contractingmovement of the operating levers. In the present invention, I havedevised a tool in which a single relative contracting movement of theoperating. levers produces only a partial closing movement of the jaws,the entire closing movement of the jaws being produced by successiverelative contracting and expanding movements of the levers. By thesuccessive contraction and expansion of the operating levers of thetool, a relastep by step movement is imparted to the jaws. Thus theratio of through which the point of application of the force appliedmoves to the distance through which the point of application of theresultant force moves against the resistance, and therefore themechanical advantage secured is much greater than .in the ordinary toolof this class. Furthermore in certain operations for which a tool ofthis character is adapted, as, for example, the cutting or severing ofan object placed between the cutting blades of the tool, it is foundthat the operation is performed with greater facility and efficiency byimparting a relative step by step movement to the jaws, so that a seriesof impulses is given to the cutting blades of the tool. In the presentinvention, the jaws are relatively actuated during each contractingmovement of the operating levers and after such actuation, the leversmay be expanded without disturbing the relative position of the jaws.

pon again contracting the. operating levers, a second impulse is givento the jaws and the said jaws are advanced a second step in theirmovement. It is, a well known fact that in operating a tool of thischaracter the operator is able to secure a more effective grip upon theoperating levers and to apply greater pressure thereupon when the leversare separated to a considerable extent than when the levers are broughtclose together. In tools which have been heretofore constructed, theextent of separation of the levers diminishes as the jaws close so thehand on the handles is diminished.- An important advantage secured by atool operating as described, consists in the fact that when theoperating levers of the tool have been contracted to actuate the jawsthe said levers may again be expanded to substantially the same relativeposition as before to enable the operator to secure a more at thedistance that the effectiveness of the grip of the sector.

' extremity of fective grip without disturbing the relative position ofthe jaws. Uponjagain contracting the operating levers, a furtherrelative movement is imparted to the jaws. The mechanism by which, inthe illustrated embodiment of the invention,"the above, and otheradvantages are secured will now be described.

In the construction illustrated, the relatively movable jaws of the toolare indicated at 1 and 2. These jaws are provided with opposed grippingfaces 3 and 4 and with opposed cutting blades 5 and 6 constructed andarranged in the usual manner. The'jaw 1 of the tool is mounted in fixedposition in a sheet metal frame 7 bent in a form substantially O-shapedincross section and embracing the. said jaw. The jaw 2 of the tool ispreferably arranged for pivotal move ment with relation to the jaw 1 andto this --end is carried by and formed integral with a lever 8 pivotallymounted between the sides of the frame 7 upon a pivot bolt or pin 9passing through a slot 10 in the lever 8, the purpose of which slot willbe hereinafter explained. A coil spring 11 interposed between the pivotpin or bolt 9 and the outer he slot 10 normally maintains the said pivotbolt in "contact with the inner extremity of the slot. A sector 13 isformed on the lever 8, the arc of which is substantially concentric withthe inner end of the slot 10, the said slot extending, radially of Thesaid sector is formed with a series of rearwardly inclined teeth 14. Alever 15 is pivoted between the sides ofthe frame 7 upon a pivot bolt orpin 16 and is provided with a toothed portion 17, the forwardly inclinedteeth of which are arranged to engage the teeth of the sector 14, asshown in Fig. 2, at a..point to the rear of the line connecting the.axes of the pivot bolts 9 and 16.so that when the lever 15 is actuatedthe said toothed portion 17 acts as a cam on the said sector. A coilspring 19' is interposed between a rearwardly extending arm 20 of theframe 7 and the lever 15 and operates the aws may to holdthe said levernormally in the position shown in Fig. 1 in engagement with the inwardlyextending shoulders 21 on the frame 7.

When there is no resistance introduced between the jaws of the tool toimpede the free relative movement of the jaws, the lever 15 ismaintained in the position shown in Fig. 1 by the coil spring 19 so thatthe teeth of the portion 17 of the lever 15 clear the teeth of thesegment13 and the jaw 2 may be moved freely about the pivot bolt 9 toopen and close the jaws. Therefore in gripping or otherwiseoperating'upon an object, be quickly adjusted to bring them intoengagement with the object. When the object is located between the jawsof the tool and the jaws are closed thereon,

the resistance of the object preventsfurther relative contractingmovement of the jaws, and the pressure applied to the levers causes thelever 15 to swing on its pivot bringing the toothed portion of saidlever into en-- the lever 15 acting on the sector 13 tends to produce arotary movement of the lever 8 about the pivot 9 and a movement of thelever along said pivot in the direction of the slot 10, thereby causingthe object to be sec'urely gripped between the gripping faces of thejaws. The toothed portion of the lever 8 is located in proximity to thepivot of said lever so that the ratio of the resultant force exerted bythe lever 8 to the pressure applied to the operating levers of the toolis very high, and a very effective gripping action is secured. In thecutting operation, the article to be severed is placed between thecutting blades of the jaws, the blades are closed thereon, and theoperating levers are gripped and actuated to throw the toothed portion17 of the lever 15 into engagement with the teeth of the sector 13 as inthe gripping operation. lVhen further pressure is now applied to theoperating levers, the; action of the toothed portion 17 of the lever 15on the sector 13 tends to produce a rotary movement of the lever 8 aboutthe pivot 9 and a movement of said lever along the said pivot, asbefore. As the levers are contracted, the cutting blades bite into theobject in this operation and the lever 8 moves along the pivot 9shifting said pivot toward the outer end of the slot 10 and compressingthe coil spring 11 between the pivot and the end of said slot, the partsassuming substantially the positions shown in Fig. 2. In theconstruction described the cooperating portions of the levers 8 and 15constitute a toggle acting to force the jaws of the tool together, thecentral point of the toggle being the point of engagement of the toothedportion 17 of the lever 15 with the .sector 13. In this singlecontracting moveis therefore much greater than in the ordinary tool.

When the grip or pressure of the hand upon the operating levers of thetool is released, the lever 15 under the action of the coil sprlng 19moves outwardly, the teeth of the portion 17 sliding over the teeth ofmower spring 10 acting against the pivot 9 and the outer end of the slot10 moves the lever 8 radially of the sector 13 restoring the pivot 9' tothe inner extremity of the slot so that the arc of the sector 13 issubstantially at the same distance from the axis of the lever 15 as inthe initial operation. When the operating levers are again gripped bythe operator, the toothed portion of the lever 17 is again brought intoengagement with the teeth of the sector 13 to actuatethe lever 8. Duringthe initial operation, however, the lever 8 has been moved angularlyabout the pivot 9 to advance the sector 13 with respect to the portion17 of the lever 15 so that upon the second engagement of the saidportion with the teeth of the sector, the said portion engages the"sector one or more teeth to the rear of its previous point ofengagement and the operating levers are separated or expanded tosubstantially the same extent as in the initial operation, enabling theoperator to obtain an efiective grip thereon. It is to be noted' alsothat the position of the point of engagement of the toothed portion ofthe o By the repeated gripping ment of the till A obtain a bettermovement of the jaws,

relatively movab lever 15 with relation to the axis of said lever and tothe pivot 9 is substantially the same as in the initial operation.Therefore the same mechanical advantageis secured for each contractingmovement of the levers. Upon a second contraction of the operatinglevers, the jaws are relatively actuated to bite further into the objectto besevered in the same manner as in the initial operation. andreleasing of the operating levers of the tool and the consequentcontraction and expansion of said levers, a step by step movement isimparted to the jaws of the tool until the object, is severed, thelevers being restored to their initial expanded position to enable theoperator to grip thereon upon each release of pressure. In the entireclosing the operating levers are repeatedly moved from expanded tocontracted position. Therefore the distance through which the point ofapplication of the force applied to each of the operating levers movesduring the same relative movejaws and therefore the mechanical advantagesecured is much greater in the tool of the present invention than intools of this class which have heretofore been devised. Although theinvention has been illustrated and described as applied to a tool provided with a pair or operating levers for actuating the jaws, certainfeatures thereof may be applied to other tools comprising le jaws, as,for example, tools in which one of the jaws is fixed and a singleoperating lever is provided for actuating the movable jaw.

Having explained the nature and object close the jaws,

of the invention and having specifically described one embodimentthereof, what is claimed is 1. A tool of the class described, having, incombination, relatively movable jaws, levers for actuating the jaws, oneof which is movable relatively to both the jaws, connections for movingsaid jaws respectively as one with the levers to. open and close thejaws, and means to produce relative workin movement of the jaws by themovement 05 one of said levers relatively to the jaws.

2. A tool of the class described, having, in combination, relativelymovable jaws, levers for actuating the jaws, one of which is movablerelatively to both the jaws, connections for moving said jawsrespectively as one with the levers to open and close the jaws, andmeans to produce relative working movement of the jaws by the movementof one of said levers relatively to the jaws, said means being effectiveonly upon the introduction of a resistance between the jaws.

3. A tool of the .class described, having,

in combination, relatively movable jaws, a lever for relativelyactuating the jaws arranged to move relatively to both the jaws, aconnection for causing one of said jaws to move as one with the lever toopen and close the jaws, and means to produce relative workin movementof the jaws by the movement 0 the lever relative to the jaws. A. A toolof the class described, having, in combination, relatively movable jaws,a lever for relatively actuating the jaws arranged to move relatively tothe jaws, a connection for causing one of said jaws to move as one withthe lever to open and close the jaws, and means to produce relativeworking movement of the jaws by the movement of the lever relatively tothe jaws, said means be ing efl'ective only resistance between the jaws.1

5. A tool of the class described, having, in combination, relativelymovable jaws, for relatively moving the jaws movable with relation toboth the jaws, means for causing one of the jaws to move as one with thelever: to open and close the jaws, and means comprising a toggleconnection operated by the movement of said lever relatively to bothjaws for imparting a relative working movement to the jaws.

6. A tool of the class described, having, in combination, relativelymovable jaws, levers for actuating the jaws, one of which is movablewith relation to both the jaws, connections for causing the jaws to moverespectively as one with the levers to open and and means for impartinga relative step-by-step working movement to the jaws by relativereciprocating movements of the levers.

' 7. A tool of the class described, having, in

a lever' its combination, relatively movable jaws, a lever forrelatively actuating the jaws movable with relation. to both the jaws; aconnection for causing one of the jaws to move as one with the lever toopen and close the jaws,

and means for imparting a relative step-bystep movement to the jaws byreciprocating movements of the lever relative to the jaws.

8. A tool of the class described, having, in combination, relativelymovable jaws, a lever for relatively actuating the jaws movable withrelation to both the jaws, a connection aw is mounted, a second jaw, acombined sliding and pivotal connection between the jaws, a leverpivoted to the frame, and connections actuated by the pivotal movementof the lever on its pivotal connection with the frame for causing thesecond jaw to slide and swing toward the first jaw.

10. A toolof the class described, having,

in combination, a'jaw, a frame upon which said jaw is mounted, a secondjaw pivotally connected with thefirst jaw, a lever pivoted to the frameand arranged to act on the sec ond jaw, connections for causing thefirst jaw to move as one with the lever to open and close the jaws, andmeans for imparting a relative working movement to the jaws by thepivotal movements of the lever on its pivotal connection with the frame.

'11. A tool of the class described, having, in combination, a jaw, aframe upon which said jaw is mounted, a second jaw pivotally connectedwith the first jaw, a lever pivoted to the frame, and intermeshingratchet teeth carried by the second jaw and the lever for imparting arelative -step-by-step movement to the jaws by the reciprocatingmovements of the lever on its pivotal connection with the frame.

12. A tool of the class described, having, in combination, a jaw, aframe upon which said jaw is mounted, a second jaw, a combined slidinand pivotal connection between the-jaws, a ever pivoted to the frame,and intermeshing teeth carried by the second jaw and the lever arrangedto cause the second jaw to slide and swing toward the first jaw as thelever is swung upon its pivotal con nection with the frame.

ISAAC W. LITCHFIELD.

Witnesses:

M. A. HURLEY, N. D. MCPHAIL.

